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Anatomy > Visceral system 2 > Flashcards

Visceral system 2 Flashcards

1
Q

The cardiac conduction system

A
  1. Sinoatrial node (SA): Initiation of the heart beat
  2. SA node signal travels to the atrioventricular node (AV) node. It slows down the activation allowing time for atria to contract
  3. From the AV node the signal travels along the AV bundle and through the bundle branhces
  4. From the AV bundle branches the signal travels to the ventricles via the Purkinje fibres
  5. Purkinje fibres spread signal to allow for rapid contractions of ventricles
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2
Q

Heart sounds

A

Systole: contraction; A chamber ejects blood
Diastole= Dilation, relaxation; A chamber fills with blood
Lub: 1st heart sound
- A closing of AV valves
- Pressure builds
- Semilunar valves open and blood is ejected
Dub= 2nd heart sound
- Closing of semilunar valves
- Blood flows from atria to ventricles
- Ventricles fill passively to 75%
Ventricular systole
- Ventricular contraction forces AV valves to shut
Atrial systole
- Atria contract and push last 25% of blood volume into ventricles
Relaxation period
- All 4 chambers in diastole
- Low pressure in ventricles

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3
Q

Innervation of the heart

A

Vagus nerve: Parasympathetic
- Decreases heart rate
- No effect on contraction
- Innervates the SA, AV nodes and coronary arteries
Sympathetic trunk
- Increases heart rate
- Increases strength of cardiac contraction
- Innervate the SA, AV node, coronary arteries and cardiac musculature
Heart receives visceral motor innervation
- Sympathetic speeds up as parasympathetic slows down the heart rate
The heart is the first organ to fully develop in the embryo: To ensure embryonic survival, the heart starts beating and pumping blood before it is fully developed

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4
Q

Development of the heart

A
  • During development, the heart has 4 unpaired chambers
  • Atria are interconnected by a hole- the foreman ovale
  • Foreman ovale closes at birth due to reversal of pressure difference between atria with dilatation of pulmonary vasculature
  • Traces remain as fossa ovalis in right atrium
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5
Q

Structure of blood vessel walls- 3 layers

A

Tunica intima= Inner simple squamous epithelium forming smooth surface of lumen
Tunica media= Middle, circularly arranged smooth muscles. Contraction/ relaxation of changes vessel diameter
Tunica external: Outer protective connective tissue layer, strengthens and anchors

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6
Q

Arteries

A
  • Blood travels from:
    1. Elastic artery (conducting)
  • Largest, low resistance, near the heart
  • High in elastin (tunica media)
  • Allows large pressure surges from the heart
  • E.g. Pulmonary trunk, aortas common carotid arteries
    2. Muscular artery
  • Distal, supply groups of organs
  • Tunica media is thicker relative to the lumen
  • Smooth muscle is sandwiched between 2 elastin layers
  • Muscular layer regulates blood flow to the organ
  • E.g. External carotid arteries, arteries of the limbs
    3. Arteriole
  • Smallest arteries, lead to capillary beds
  • Thin tunica media of smooth muscle cells
  • Contraction/ relaxation regulated via local signals or the sympathetic nervous system
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6
Q

Arteries vs veins

A
  • Arteries carry blood away from the heart and veins carry blood to the heart
  • All arteries in the systemic circuit carry oxygenated blood and all veins in the systemic circuit carry de-oxygenated blood
  • But the pulmonary circuit is switched
  • Pulmonary arteries carry de-oxygenated blood
  • Pulmonary veins carry oxygenated blood
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7
Q

Capillaries

A
  • Smallest blood vessels (diameter with single blood cells)
  • Single layer of endothelial cells
    3 types of capillaries
  • Continuous: Most common, least permeable
  • Fenestrated: Have pores for high exchange rates
  • Sinusoid: Very leaky for high exchange of large molecules
  • Capillary bed: Network of capillaries that supply blood tissues
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8
Q

Veins

A
  • Transport blood from capillaries to the heart
  • Venules: Smallest veins, joins to form veins
  • Veins carry 65% of the body’s blood
  • Compared to arteries, veins have: Larger lumen, thicker tunica externa than tunica media, less elastin, thinner walls
  • Skeletal muscular pumps to aid flow back to the heart
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9
Q

Veins have valves

A

Veins have low blood pressure, so how does blood get back to the heart?
- In folds of the tunica intima create valves to allow for unidirectional flow of blood
- Valves are opened by blood flow to the heart and closed by back flow: aided by skeletal muscle pumps
- Most abundant in limbs

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10
Q

Branches of the arch of the aorta and artery of head and neck

A

3 arteries originate from the arch:
1. Brachiocephalic trunk: right common carotid artery and right subclavian artery
2. Left common carotid artery
3. Left subclavian artery
Arteries of the head and neck
- 4 pairs (left and right arteries)
1. Common carotid artery
2. Vertebral artery
3. Thryocervical trunk
4. Costocervical trunk

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11
Q

Branches of the thoracic aorta

A

Numerous small branches to the thoracic viscera and posterolateral wall
- The anterior thoracic and upper ab wall are supplied by branches of the subclavian arteries: internal thoracic arteries
Also serves the
- Pericardium
- Lungs and branch
- Esophagus
- Not the heart which has already received its supply from coronary arteries

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12
Q

Blood supply to the brain

A

The brain requires a constant blood supply: A disruption of seconds loss of consciousness, and minutes can be life-threatening
- Branches of the left and right internal carotids and the left and right vertebral arteries supply the brain
Circle of Willis- an arterial anastomosis that provides alternate routes for blood to reach brain areas it occlusion

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13
Q

Branches of the abdominal aorta

A

3 unpaired arteries that supply the gastrointestinal tract and spleen:
1. Celiac artery
2. Superior mesenteric artery
3. Inferior mesenteric artery
3 paired arteries
1. Suprarenal arteries
2. Renal arteries
3. Gonadal arteries
The abdominal aorta ends by dividing into 2 common iliac arteries which, in turn, divide into:
- Internal iliac arteries (pelvic organs, genitals)
- External iliac arteries (lower limbs)

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14
Q

Arteries of the upper and lower limbs

A

UL
Subclavian artery -> under clavicle, Axillary artery-> brachial artery -> radial and ulnar arteries
LL
Femoral artery (hip joint, thigh muscles) -> popliteal artery (knees) -> anterior and posterior tibial arteries
The anterior tibial artery branches to the dorsal pedis artery and digital arteries extend from the plantar arch and supply the toes
Posterior tibial artery branches to: Fibula artery and medial and lateral plantar arteries

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15
Q

Systemic blood returns to the heart via 3 veins

A
  • Superior vena cava: receives blood from the body superior to the diaphragm (except lungs) and drains into the right atrium (arises from right and left brachiocephalic)
  • Inferior vena cava: Receives most of the blood from the body inferior to the diaphragm - drains into the right atrium
  • Coronary sinus: Receives blood from the heart
16
Q

Veins of the head and neck

A
  • Most blood drains the head and neck via 3 veins
  • Internal jugular: receive blood from rural venous sinuses
  • External jugular: receive blood from posterior and lateral scalp and some of face
  • Vertebral veins: Receive blood from the cervical vertebrae and spinal cord, superior neck muscles
17
Q

Hepatic portal vein branches

A
  1. The inferior mesenteric drains the distal part of the large intestine; and receives blood from the superior rectal vein, sigmoid veins and left colic vein
  2. The splenic vein drains the spleen: and receives blood from pancreatic veins, short gastric veins, and the right gastroepiploic vein
  3. The superior mesenteric vein drains the small intestine and part of the large intestine; and receives blood from the intestinal veins, pancreaticoduodenal veins, ileocolic vein and right and middle colic veins
18
Q

Veins of the upper limb

A

Deep veins
- The digital veins; superficial and deep palmar venous arches drain into the radial veins and ulnar veins
- The radial and ulnar veins merge to form a pair of brachial veins
- Brachial veins and the basilic vein merge to form the axillary vein
- The axillary vein is renamed the subclavian rein
Superficial veins
- Basilic vein runs adjacent to the medial surface of the upper limb and eventually helps form the axillary vein
- Cephalic vein: runs alongside the lateral aspect of the upper limb and drains the axillary vein
- Median cubital vein: Interconnects the basilic and cephalic veins

19
Q

Veins of the abdomen

A
  • The abdominal wall, the gonads, the liver, the kidney, the suprarenals glands and the diaphragm are drained by the inferior vena cava
  • The visceral organs within the abdominal cavity all drained by the hepatic portal vein
  • The abdominal portion of the inferior vena cava collects blood from 6 major veins
    1. Lumbar veins
    2. Gonadal veins
    3. Renal veins
    4. Suprarenal veins
    5. Hepatic veins
    6. Phrenic veins ss

Anatomy (8 decks)

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